There are a great variety of chucks that are conventionally known, including so-called “non-contact” chucks. Generally, a non-contact chuck makes little or no mechanical contact with a first, e.g., a non-process, surface of a substrate to be held. A popular type of non-contact chuck is the so-called Bernoulli type.
Such chucks operate to lift a substrate, e.g., which may include and is often referred to herein as a wafer, above a surface by introducing a current of gas underneath and most often rotate the wafer simultaneously. Such chucks operate with a second, e.g., process, side facing upwards. This may be a poor arrangement in situations where face-down applications call for holding the wafer with its side to be processed facing down.
There are other conventional non-contact types of chucks that can operate facing down, but these suffer from instability and often draw chemicals and/or contaminants onto the second or backside, e.g., non-process side, of the substrate.